The Patients Association said people will be forced to wait longer for operations while in pain.

There are around 25,000 routine operations carried out in the NHS in Britain each day, including hernia repairs, joint replacements, hysterectomies and cataract removal.

The day of industrial action was called after a ballot of 104,000 BMA members returned overwhelming support for action and a 50 per cent turnout.

Dr Hamish Meldrum, chairman of the BMA Council admitted there would be disruption and inconvenience to patients but the over-riding concern was that patient safety would not be compromised.

He said: “This is not a step that doctors take lightly – this is the first industrial action doctors have taken since 1975.

"We have consistently argued that the Government should reconsider its position, and even at this stage we would much prefer to negotiate a fairer deal than to take action. We are not seeking preferential treatment but fair treatment.

The impact of the action on June 21st will be assessed before any decision is taken on whether a further day of action is called, Dr Meldrum said.

A spokesman for the BMA said patients who already have operations or appointments booked for June 21st do not need to contact their hospital or GP surgery. They will be contacted when decisions have been made about which patients will be seen.

Roswyn Hakesley-Brown, chairman of the Patients Association said: “Although we recognise that the BMA will target this strike at non urgent care, we have real concerns about the possible impact this will have on patients.

"The distinction between an urgent and a non urgent case may not be clear, and as a result time may be lost in cases where treatment is needed urgently.

"In addition, at a time when people are already waiting longer for elective surgical procedures, further cancellations of those operations will not be welcomed by those waiting in pain for a hip or knee replacement.

"I hope that a solution can be found before any strikes occur.”

Andy Burnham, Shadow Health Secretary, said: "This result reflects the clear strength of feeling in the profession at the arrogance of a Government attacking public services from every angle.

"It's the BMA's right to make their own decision, but even at this stage I would urge doctors to pull back from any form of action that damages patient care, including disruption to non-urgent care.

"Instead, I would urge the BMA to follow other routes in making clear the substance of their disagreement with the Government."

Julia Manning, chief executive of the think tank, 2020health said: “This is a massive own goal for doctors that tarnishes them all with a ‘greedy’ brush. Many of my friends in medicine will be horrified and embarrassed at the thought of their colleagues striking.

“This vote says that they are more concerned with pensions than patients and is a morally unjustifiable position.

"Doctor’s pensions will still be one of the best in UK and striking will achieve nothing because there is no more money.

“By taking industrial action, many more people will be aware of just how generous their pension still is and all doctors will be seen as greedy and stingy as a result of their colleagues’ action.

"The public were aghast at the £26k welfare benefit cap – they will think even worse of doctors striking over a pension worth more that £50,000 a year."

Doctors were warned they needed to be careful their patients would be looked after it they were turned away.

Dr Mike Devlin, head of advisory services at the Medical Defence Union, which provides legal advice to doctors, said: "Where doctors are contemplating industrial action it is important that they are mindful of their professional obligations towards patients, as outlined by the GMC, and that patient safety is not compromised.

"Doctors who opt not to provide certain services during a period of industrial action should be prepared to justify the arrangements that they put in place to meet patient needs during that period."

Health Secretary Andrew Lansley said: “The public will not understand or sympathise with the BMA if they call for industrial action over their pensions.

“People know that pension reform is needed as people live longer and to be fair in future for everyone. We have been clear that the NHS pension scheme is, and will remain, one of the best available anywhere.

“Every doctor within 10 years of retirement will receive the pension they expected, when they expected.

"Today's newly qualified doctor who works to 65 will get the same pension as the average consultant retiring today would receive at 60 - the BMA have already accepted a pension age of 65. If doctors choose to work to 68 then they could expect to receive a larger pension of £68,000."